Fire retardant and thermal blankets have been used to provide thermal protection to electrical transmission systems, devices and equipment at temperatures up to 2000.degree. F. for periods of one-half hour (1/2 hr.) to three hours (3 hrs.). Typical electrical transmission systems requiring such thermal protection include cables, conduits, cable trays, junction boxes, hangars, thermal shorts, condulets, transmission lines, and other electrical transmission devices associated with the transmission of electricity and electrical signals; and gas and oil pipelines. These types of fire retardant and thermal blankets used in protective wrapping systems have multiple facility applications for operational uses that include coal, gas or oil generating plants; electrical and gas utilities; power generating stations; nuclear power generating facilities; power distribution stations; chemical and pharmaceutical manufacturing facilities; shipping and marine facilities; military installations; telecommunication facilities; airports and the like.
There are two basic types of thermal protection wrapping systems that provide fire and heat protection: 1.) thermal insulation systems and 2.) endothermic systems. Thermal insulation systems rely on wraps, typically ceramic blankets, for reducing thermal conductivity and thereby reducing the temperature rise within the electrical transmission system. Endothermic systems rely on thermal materials that absorb heat from the source, thereby reducing the amount of heat transmitted to the electrical transmission system being protected. Typically, thermal blankets used in thermal insulation systems are bulky, requiring a large amount of space that often is not available. Materials used in endothermic systems are typically very heavy and expensive, and require additional supports or reinforcements for the system. In some cases, the additional weight cannot be accommodated, due to seismic limitations of the facility.
Thus, the current thermal protection wraps used to protect electrical transmission systems for long periods, in excess of three hours, are typically expensive, heavy, difficult and cumbersome to install, and have a large diameter. The limitations for practical application of these wrapping system products are very severe.
Currently, there is no single thermal protection wrapping system having all of the following desirable features:
1. Low heat transmission to the electrical transmission device; PA1 2. Absorption of excess heat generated from the electrical transmission device; PA1 3. Ease of installation on all types and configurations of conduits, cable trays, transmission lines, cables and the like including bends, thermal shorts, hangars and areas near walls and other confined areas; PA1 4. Easily adaptable for variations of configurations encountered during onsite installation; PA1 5. Dry application of thermal material layers for the protection of the electrical transmission device, requiring no liquids or any drying time; PA1 6. A light-weight thermal protection wrapping system, thereby eliminating the requirements for reinforcements and additional supports to the wrapped electrical transmission device; PA1 7. Low ampacity deration within the electrical transmission devices, as in conduits, cables, transmission lines and the like; PA1 8. Multiple facility applications for operational use in coal, gas or oil generating plants; electrical and gas utilities; power generating stations; nuclear power generating facilities; power distribution stations; chemical and pharmaceutical manufacturing facilities and the like; and PA1 9. Entirely passive system, requiring no active devices.
Additionally, in some applications the current thermal protection wrapping systems are impractical for reasons other than fire and heat protection, as the wrapping system may lack resistance to water and chemicals, impact resistance, temperature fluctuation resistance and resistance to other environmental factors; and because of these factors, these wrapping systems are limited in their applications.
There remains a need for a new and improved thermal protection wrapping system that would provide substantial protection from fire and heat to electrical transmission devices for a long duration of time if a fire were to occur by reducing the flammability of the materials within the composite laminate structure, without adding a large amount of size and weight to the wrapping system. In addition, the thermal protection wrapping system should be easy to install and durable; and adaptable for use on many configurations and types of electrical and transmission equipment.